It's the one that comes out of the bottom of the boiler unit. Could it
be that the water pressure, controlled by a gate valve under the sink,
is too high?

John wrote:
"MarkF" wrote in message
oups.com...
My Ferroli Combi boiler is leaking from the overflow pipe. Is there any
obvious reason for this happening and is there a simple fix? I am new
to Combi-boilers and am not sure how they work.


Which overflow - one from a loft storage tank - or a pipe on the boiler. If
the latter, it could be a poor seating in the pressure release valve.

Can you clarify then I am sure you will get some good responses.